Sunny, you might try posting this question on YPKO, if you haven't already.
I don't do much voice editing (I'm more into editing styles), but there are one or two on YPKO that dabble with voice editing and who are getting great results...and, best of all, sharing them.
Here is the link.
http://www.yamahapkowner.com/forum/index.php Best wishes,
Ian
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Yamaha Tyros4, Yamaha MS-60S Powered Monitors(2), Yamaha CS-01, Yamaha TQ-5, Yamaha PSR-S775.